Genetic relatedness of Plasmodium falciparum isolates and the origin of allelic diversity at the merozoite surface protein-1 (MSP-1) locus in Brazil and Vietnam.

Hoffmann EH, Ribolla PE, Ferreira MU - Malar. J. (2003)

Bottom Line:
At least one epidemic clone propagating in Brazil remained relatively unchanged over more than one decade.Moreover, we found no evidence that rearrangements of MSP-1 repeats, putatively created by mitotic recombination events, generated new alleles within clonal lineages of parasites in either country.Identical MSP-1 alleles originated from co-ancestry in both populations, whereas nearly identical MSP-1 alleles have probably appeared independently in unrelated parasite lineages.

Results: The low pair-wise average genetic distance between microsatellite haplotypes of isolates sharing identical MSP-1 alleles indicates that epidemic propagation of discrete parasite clones originated most identical MSP-1 alleles in parasite populations from Brazil and Vietnam. At least one epidemic clone propagating in Brazil remained relatively unchanged over more than one decade. Moreover, we found no evidence that rearrangements of MSP-1 repeats, putatively created by mitotic recombination events, generated new alleles within clonal lineages of parasites in either country.

Mentions:
The levels of genetic diversity of Vietnamese isolates, based on 9 microsatellite loci, were about two times higher than those observed in Brazil: the number of alleles at each locus ranged between 3 and 11 (average, 5.44), with estimates of expected heterozygosity ranging between 0.52 and 0.91 (average, 0.72) (Table 1). The overall genetic relatedness of Vietnamese isolates is represented in Figure 3. Both pairs of isolates with identical haplotypes (V57-V10 and BL199-BL185) also shared identical MSP-1 alleles (respectively #13 and #33). The average genetic distance of isolates sharing identical MSP-1 alleles (0.568; 9 pair-wise comparisons) was significantly lower (P = 0.008) than that estimated for isolates with different MSP-1 alleles (0.715; 244 pair-wise comparisons). Thus, microsatellite data also provided evidence that identical MSP-1 alleles in Vietnam tend to occur in genetically related parasites.

Mentions:
The levels of genetic diversity of Vietnamese isolates, based on 9 microsatellite loci, were about two times higher than those observed in Brazil: the number of alleles at each locus ranged between 3 and 11 (average, 5.44), with estimates of expected heterozygosity ranging between 0.52 and 0.91 (average, 0.72) (Table 1). The overall genetic relatedness of Vietnamese isolates is represented in Figure 3. Both pairs of isolates with identical haplotypes (V57-V10 and BL199-BL185) also shared identical MSP-1 alleles (respectively #13 and #33). The average genetic distance of isolates sharing identical MSP-1 alleles (0.568; 9 pair-wise comparisons) was significantly lower (P = 0.008) than that estimated for isolates with different MSP-1 alleles (0.715; 244 pair-wise comparisons). Thus, microsatellite data also provided evidence that identical MSP-1 alleles in Vietnam tend to occur in genetically related parasites.

Bottom Line:
At least one epidemic clone propagating in Brazil remained relatively unchanged over more than one decade.Moreover, we found no evidence that rearrangements of MSP-1 repeats, putatively created by mitotic recombination events, generated new alleles within clonal lineages of parasites in either country.Identical MSP-1 alleles originated from co-ancestry in both populations, whereas nearly identical MSP-1 alleles have probably appeared independently in unrelated parasite lineages.

Results: The low pair-wise average genetic distance between microsatellite haplotypes of isolates sharing identical MSP-1 alleles indicates that epidemic propagation of discrete parasite clones originated most identical MSP-1 alleles in parasite populations from Brazil and Vietnam. At least one epidemic clone propagating in Brazil remained relatively unchanged over more than one decade. Moreover, we found no evidence that rearrangements of MSP-1 repeats, putatively created by mitotic recombination events, generated new alleles within clonal lineages of parasites in either country.